1. Field of the Invention
The present invention relates to liquid fuel burning heaters, and more particularly to compact, self-contained heater units suitable for use in vehicles and which comprise a liquid-fuel-fed burner and a heat exchanger arranged in alignment therewith inside a housing.
2. Description of the Prior Art
Heating units of this kind are normally mounted in the passenger compartment of the vehicle or in some compartment which is open to the passenger compartment. Because of the obsolute necessity of preventing the penetration of exhaust gases into the passenger compartment, very stringent requirements are set for the gas-tightness of all conduits and compartments of a heating unit through which exhaust gases may travel. In the past, it has been largely overlooked that the ignition plug of the heater unit, by virtue of its removability, represented a potential source of exhaust gas leaks.